The subject matter herein relates generally to electronic devices, such as transformers, inductors, bluns, couplers, or filters.
Some known electronic devices include planar bodies, such as circuit boards, that include one or more magnetic components built into the planar bodies. The magnetic component can include a ferrite core with conductive winding extending around the ferrite core. Some of these magnetic components include two conductive windings that are not conductively coupled with each other. For example, the conductive windings may not be physically or mechanically coupled such that electric current cannot flow through one conductive winding directly onto the other conductive winding. The current flowing through one winding generates a magnetic field in the core and in the other winding. The magnetic field in the other winding generates an electric current in the other winding. The electronic performance of the device can be determined by a variety of parameters, such as the ratio of the number of turns in the first winding to the number of turns in the second winding, the shape of the first and/or second windings, the impedance of the first and second windings, and the like.
The manufacturing process of some known planar electronic devices having magnetic components includes depositing layers of thermoset materials, such as FR-4, on a substrate that includes the ferrite core. The thermoset layers may be planarized before depositing additional conductive layers or bodies that form the conductive loops around the ferrite core. The planarizing of the thermoset layers may include sanding or otherwise removing rough or undulating portions of the thermoset layers. Some known manufacturing processes can damage the ferrite core in several magnetic components in a substrate due to relatively large variability in the vertical positions of the ferrite cores. For example, some of the ferrite cores may not be fully within the thickness of the substrate and thus may project from one of the sides of the substrate. The projecting portions of the ferrite cores can be mechanically damaged by the planarization of the thermoset layers. Damage to the ferrite cores can result in relatively large variations in the electric impedance characteristics of the magnetic components in a substrate. Additionally, mechanical stress may be imparted on the ferrite core and/or the electronic performance of the electronic device may be reduced if the ferrite core is asymmetrically located or placed within the substrate.
A need exists for a planar electronic device having a magnetic component and a method for manufacturing such a device that avoids damaging the ferrite cores of the devices.